In a current communication system, to avoid occurrence of a fault or congestion in a core network, a network operation and management (OAM) center node, after acquiring load information of the core network, generates access control information for controlling a user equipment to access the core network or a core network node, and configures the access control information for a serving radio access network node through an interface between the OAM and the serving radio access network node. After acquiring the access control information from the OAM, the serving radio access network node may send, by using a system broadcast message of a cell on a radio access network (RAN) side, an access control parameter to user equipments (UEs) of different access classes, to indicate whether access to the core network is permitted. The access control parameter may be domain specific access control (DSAC) information, and may also be paging permission access control (PPAC) information.
A principle of using DSAC information to control a user equipment accesses the core network is as follows: After receiving and stores the access control information acquired from the system broadcast message of the cell and when initiating a new service to a specific core network node, the UE determines an access control (AC) value stored in a subscriber identity module (SIM) card, and determines DSAC information corresponding to the AC value; and if a value of the DSAC information is Barred (Barred), the UE cannot attempt to access the core network; or if a value of the DSAC information is Not Barred (Not Barred), the UE can attempt to access the core network. In this way, load control is implemented for the core network node.
Similarly, a principle of using PPAC information to control the user equipment accesses the core network is as follows: After entering a cell, the UE receives PPAC information from a broadcast channel of the cell; after receiving a paging message and when the UE initiates a response message in response to the paging message, or initiates a location update (e.g. Location Update or Registration Update) message, or initiates a registration procedure to the network, the UE first determines a value of the PPAC information received from the broadcast channel of the cell; and if the value of the PPAC information is Not Barred, the UE may initiate the paging response message or the location update message or the registration message; or if the value of the PPAC information is barred, the UE needs to further determine whether the network wishes to bar access to a circuit switched (CS) domain or bar access to a packet switched (PS) domain.
In the current communication system, the DSAC/PPAC information is access control information based on a cell level, and can only be broadcast in a system broadcast message. Assuming that the UE has established a connection with a core network domain, for example, has established a connection with the CS domain, a cell change or handover occurs due to reasons of mobility and the like in a CS call process of the UE, and load information of a PS domain core network node, for example, a serving GPRS support node (SGSN, “GPRS” stands for general packet radio service), to which a new serving radio network controller (RNC) is connected is changed after the handover, or access control information in a new serving cell is changed due to a change of an SGSN. However, for a UE in a non cell dedicated channel (CELL_DCH) state, the UE cannot read a system broadcast message while transmitting and receiving data on a dedicated channel. As a result, the UE is unable to update the stored access control information according to the access control information of the new serving cell, and consequently, before the UE initiates a new PS call request, the UE cannot properly determine whether to initiate an access request to the core network.